Chinese government has allegedly cracked the encryption of Apple's AirDrop
The Chinese authorities have apparently managed to obtain the numbers and email addresses of iPhone owners who distribute content via AirDrop. Apparently, this is a common method of communication among members of pro-democracy movements.
Chinese forensic experts from a state institute have apparently succeeded in decrypting Apple's AirDrop protocol using a hash value (checksum used for encrypting messages of variable length). This is reported by the portal Bloomberg, which in turn refers to a notification from the Beijing judicial administration. AirDrop is a service for sharing content between Apple devices that are in close proximity to each other.
The reason for this effort was apparently because AirDrop is used for the distribution of "inappropriate content". Because it is anonymous and difficult to track, this method is finding more and more imitators, according to the Chinese press release. It is now important to identify these senders as quickly as possible.
AirDrop creates "short identity"
The identification has apparently already been successful several times. This is due to the hash function that AirDrop uses as soon as the sharing menu is opened. If users are logged in to iCloud, the operating system generates a short identity. At least when an AirDrop transfer takes place. This allows Apple devices to recognise other Apple devices.
This hash value, in turn, is based on the data stored for the Apple ID. For example, telephone numbers and email addresses. Using so-called rainbow tables, the Chinese authorities were able to recalculate the hash value and thus decrypt it.
Dissidents may be tied back
As the New York Times reports, AirDrop has been used by pro-democracy activists for several years. In 2022, for example, to draw attention to the protests in Hong Kong and spread anti-government messages. The idea of restricting such movements may also have played a role in the efforts to crack AirDrop encryption.
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I've been tinkering with digital networks ever since I found out how to activate both telephone channels on the ISDN card for greater bandwidth. As for the analogue variety, I've been doing that since I learned to talk. Though Winterthur is my adoptive home city, my heart still bleeds red and blue.